This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-089290, filed Mar. 28, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to a semiconductor device having a capacitor and a method of manufacturing the same.
In recent years, proposed is a semiconductor device using a Cu wiring of a damascene structure in accordance with progress in the fineness of the element.
FIG. 16 is a cross sectional view showing a conventional semiconductor device of a damascene structure. As shown in the drawing, a first wiring 62 made of, for example, Cu is formed in a SiO2 film 61, and a dielectric film 63 is formed on the first wiring 62. Further, an upper electrode 64 is formed on the dielectric film 63. Still further, a via hole 66 connected to the upper electrode 64 is formed in an interlayer insulating film 65, and a second wiring 67 made of, for example, Cu, which is connected to the via hole 66, is formed on the interlayer insulating film 65.
In the conventional semiconductor device of the construction described above, the first wiring 62, the dielectric film 63 and the upper electrode 64 collectively form a capacitor 68. In other words, the first wiring 62 buried in the SiO2 film 61 plays the role of the lower electrode of the capacitor 68. The first wiring 62 is hereinafter referred to as a lower electrode.
However, in the conventional semiconductor device of the construction described above, the capacitance of the capacitor 68 is determined by the surface area of any of the lower electrode 62 and the upper electrode 64 having a smaller surface area. Therefore, where a capacitor having a large capacitance is required, it is necessary to enlarge the surface area of not only the upper electrode 64 but also the lower electrode 62. Such being the situation, it was very difficult to form a capacitor having a large capacitance while promoting the fineness of the element.
FIG. 17 shows in a magnified fashion the portion B shown in FIG. 16. As shown in FIG. 17, an edge portion 64a of the upper electrode 64 on the side of the dielectric film 63 forms an acute angle, with the result that the electric field is concentrated on the edge portion 64a, giving rise to a problem that the reliability of the element is lowered.
Further, although many of the capacitors used as analog passive elements are capacitors fixed at one kind of capacitance, there is a case where it is required to form within a single layer a plurality of capacitors having various capacitance values. For example, in order to cope with the pairing problem of the capacitors which occur nonuniform capacitance values that the capacitance values are rendered nonuniform among the capacitors, it is considered effective to diminish the influence given by the nonuniform capacitance values. However, if the area of the capacitor is increased, the delay time accompanying the charging is rendered long, making it necessary to diminish the capacitance per unit area of the capacitor because the capacitor having a small capacitance permits shortening the charging time so as to shorten the delay time accompanying the charging. For meeting such demands, it has become necessary to form a plurality of capacitors having at least two kinds of capacitance values within a single layer without increasing the chip area.
As described above, it was very difficult in the conventional semiconductor device to form a plurality of capacitors having a large capacitance or at least two kinds of capacitance values while promoting the fineness of the element. An additional problem to be noted is that an electric field is concentrated in an edge portion of the electrode so as to lower the reliability of the element.
An object of the present invention, which has been achieved for overcoming the above-noted problems inherent in the prior art, is to provide a semiconductor device, which permits forming a capacitor having a large capacitance or a plurality of capacitors having at least two kinds of capacitance values while promoting the fineness of the element, and which also permits moderating the electric field concentration, and a method of manufacturing the same.
The particular object of the present invention can be achieved by the means described below.
According to a first aspect of the present invention, there is provided a first semiconductor device, comprising a first wiring formed in a first insulating film; a second insulating film formed on the first insulating film; a first electrode film selectively formed on the second insulating film; a third insulating film formed on the first electrode film, and having an end portion and a central portion, wherein the end portion has a thickness thinner than the central portion; a second electrode film formed on the central portion of the third insulating film such that the second electrode film faces the first electrode film; a fourth insulating film formed on the second electrode film and the end portion of the third insulating film; a fifth insulating film formed on the fourth insulating film; a sixth insulating film formed on the fifth insulating film; a seventh insulating film formed on the first interlayer insulating film; second, third and fourth wirings formed in the seventh insulating film; a first connecting member formed in the sixth, fifth and fourth insulating films to electrically connect the second wiring to the second electrode film; a second connecting member formed in the sixth, fifth and fourth insulating films and the end portion of the third insulating film to electrically connect the third wiring to the first electrode film; and a third connecting member formed in the sixth and second insulating films to electrically connect the fourth wiring to the first wiring.
The first and second electrode films and the third insulating film form a capacitor.
It is desirable for the side surface of the second connecting member is only in contact with the fourth and fifth insulating films.
Further, it is desirable for the seventh insulating film to be formed of an insulating film having a low dielectric constant.
Also, it is desirable for the second, fourth and fifth insulating films are a diffusion preventing film.
According to a second aspect of the present invention, there is provided a second semiconductor device, comprising a first wiring formed in a first insulating film; a second insulating film formed on the first insulating film; a first electrode film selectively formed on the second insulating film; a third insulating film selectively formed on the first electrode film and the second insulating film; a second electrode film formed on the third insulating film such that the second electrode film faces the first electrode film; a second wiring formed on the second electrode film; a third wiring formed on the second insulating film and positioned apart from the second wiring; a first connecting member formed in the second insulating film to electrically connect the first electrode film to the first wiring; and a second connecting member formed in the second insulating film to electrically connect the third wiring to the first wiring.
The first and second electrode films and the third insulating film form a capacitor.
According to a third aspect of the present invention, there is provided a third semiconductor device, comprising a first wiring formed in a first insulating film; a second insulating film formed on the first insulating film; a first electrode film selectively formed on the second insulating film in a manner to overlap partially with the first wiring; a third insulating film selectively formed on the first electrode film; a second electrode film formed on the third insulating film such that the second electrode film faces the first electrode film; a fourth insulating film formed on the first and second electrode films and the second insulating film; a fifth insulating film formed on the fourth insulating film; second, third and fourth wirings formed in the fifth insulating film; a first connecting member formed in the fourth and second insulating films to electrically connect the second wiring to the first wiring; a second connecting member formed in the fourth insulating film to electrically connect the third wiring to the second electrode film; and a third connecting member formed in the fourth insulating film to electrically connect the fourth wiring to the first electrode film.
The first wiring, the first electrode film and the second insulating film form a first capacitor, and the first and second electrodes and the third insulating film form a second capacitor, the first and second capacitors differing from each other in the capacitance.
It is desirable for the fifth insulating film to be formed of an insulating film having a low dielectric constant.
According to a fourth aspect of the present invention, there is provided a method of manufacturing the first semiconductor device, comprising the steps of forming a first wiring in a first insulating film; forming a second insulating film on the first insulating film; forming a first electrode film on the second insulating film; forming a third insulating film on the first electrode film, and having an end portion and a central portion; forming a second electrode film on the third insulating film; removing the second electrode film and the third insulating film to an extent that the first electrode film is not exposed to the outside, and forming the end portion of the third insulating film thinner than the central portion of the third insulating film; forming a fourth insulating film on the second insulating film and the end portion of the third insulating film; selectively removing the fourth insulating film, the end portion of the third insulating film and the first electrode film; forming a fifth insulating film on the fourth and second insulating films; forming a sixth insulating film on the fifth insulating film; forming a seventh insulating film on the sixth insulating film; forming a first connecting member electrically connected to the second electrode film within the sixth, fifth and fourth insulating films, forming a second connecting member electrically connected to the first electrode film within the sixth, fifth and fourth insulating films and the end portion of the third insulating film and forming a third connecting member electrically connected to the first wiring within the sixth, fifth and second insulating films; and forming second, third and fourth wirings connected to the first, second and third connecting members within the seventh insulating film.
According to a fifth aspect of the present invention, there is provided a method of manufacturing the second semiconductor device, comprising the steps of forming a first wiring in a first insulating film; forming a second insulating film on the first insulating film; forming first and second connecting members electrically connected to the first wiring within the second insulating film; forming a first electrode film connected to the first connecting member on the second insulating film; forming a third insulating film on the first electrode film and the second insulating film; forming a second electrode film on the third insulating film; selectively removing the second electrode film and the third insulating film so as to expose the second connecting member; and forming a second wiring on the second electrode film and forming a third wiring positioned apart from the second wiring and connected to the second connecting member on the second insulating film.
According to a sixth aspect of the present invention, there is provided a method of manufacturing the third semiconductor device, comprising the steps of forming a first wiring in a first insulating film; forming a second insulating film on the first insulating film; selectively forming a first electrode film on the second insulating film in a manner to overlap partially with the first wiring; selectively forming a third insulating film on the first insulating film; forming a second electrode film on the third insulating film; forming a fourth insulating film on the first and second electrode films and the second insulating film; forming a fifth insulating film on the fourth insulating film; forming a first connecting member electrically connected to the first wiring within the fourth and second insulating films, forming a second connecting member electrically connected to the second electrode film within the fourth insulating film and forming a third connecting member electrically connected to the first electrode film within the fourth insulating film; and forming second, third and fourth wirings connected to the first, second and third connecting members within the fifth insulating film.
According to the present invention described above, it is possible to provide a semiconductor device, which permits forming a capacitor having a large capacitance or a plurality of capacitors having at least two kinds of capacitance values while promoting the fineness of the element, and which also permits moderating the electric field concentration, and a method of manufacturing the particular semiconductor device.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.